Pump Device

ABSTRACT

A centrifugal pump includes a pump body that defines a partition between a rotor chamber and a pump chamber, a motor case that forms the rotor chamber together with the pump body, a pump cover that forms the pump chamber together with the pump body, and a bearing that rotatably supports a rotor shaft of a rotor with respect to the pump body. The pump body includes a boss part that projects from a partition wall toward the rotor chamber and rotatably supports the bearing. A projection part projects from a lateral section of the boss part. The projection part has an inclined surface section inclined radially inward toward the leading end side of the boss part. The boss part has a connection hole that extends from the rotor chamber to the pump chamber. A rotor chamber side opening end portion of the connection hole opens to the inclined surface section.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 35 U.S.C. § 371 U.S. National Stage Entry application claiming priority to PCT Patent Application No. PCT/JP2019/049121, filed Dec. 16, 2019, which claims priority to Japanese Patent Application No. 2018-244385, filed Dec. 27, 2018, each of which is incorporated herein by reference in its entirety for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND

The present disclosure relates generally to pump devices.

Japanese Unexamined Patent Publication No. 2012-17712 describes an example of turbomachine used as a pump for pumping gas. The turbomachine includes a motor portion with a rotor rotatably disposed in a rotor chamber. The turbomachine also includes a pump portion including an impeller rotatably disposed in a pump chamber and coupled to the rotor. Further, the turbomachine includes a partition wall, a motor case, a pump cover, and a bearing. The partition wall provides a partition between the rotor chamber and the pump chamber. The motor case together with the partition wall forms the rotor chamber. The pump cover together with the partition wall forms the pump chamber. The bearing rotatably supports the rotor shaft of the rotor with respect to the partition wall. The partition wall has a boss part that projects from the partition wall to the rotor chamber side. The boss part supports the bearing. The boss part includes a linear connection hole formed therein that penetrates in the axial direction and connects the rotor chamber and the pump chamber.

SUMMARY

One configuration of the present disclosure is a pump device comprising a partition wall that provides a partition between a rotor chamber and a pump chamber, a motor case, a pump cover, and a bearing. The rotor is rotatably disposed in the rotor chamber. The impeller is coupled to the rotor and is rotatably disposed in the pump chamber. The motor case forms the rotor chamber together with the partition wall. The pump cover forms the pump chamber together with the partition wall. The bearing rotatably supports the rotor shaft of the rotor with respect to the partition wall. The partition wall has a boss part that projects from the partition wall to the rotor chamber side and that supports the bearing. At a lateral section of the boss part, a projection part has an inclined surface section inclined radially inward toward the leading end side of the boss part. The boss part has formed therein a connection hole that connects the rotor chamber and the pump chamber. A rotor chamber side opening end of the connection hole opens to the inclined surface section.

According to the above configuration, when the connection hole is drilled in the oblique direction in the boss part of the partition wall, a machining tool, such as a drill bit, may orthogonally or substantially orthogonally abut the inclined surface portion of the projection part of the boss part. Therefore, when the connection hole is drilled in the oblique direction in the boss part of the partition wall, workability may be improved, as compared with that of Japanese Unexamined Patent Application No. 2012-17712. Further, if grease has been injected into the bearing, gas in the pump chamber flows through the connection hole while bypassing the bearing, so that grease loss from the bearing may be suppressed. Furthermore, since the projection part projects from the lateral section of the boss part, the rigidity of the boss part supporting the bearing may be increased. This may suppress shaft runout of the rotor shaft of the rotor as compared with the case where the projection part does not project from the boss part. Therefore, it is possible to suppress an increase in the amount of heat generated by the bearing, thereby suppressing thermal deterioration of the bearing due to heat. As a result, the life of the pump may be improved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view schematically illustrating a centrifugal pump according to a first embodiment.

FIG. 2 is a cross-sectional view of the centrifugal pump of FIG. 1 taken along line II-II in FIG. 1.

FIG. 3 is an enlarged cross-sectional view of the pump part of the centrifugal pump of FIG. 1.

FIG. 4 is a bottom view of the pump body of FIG. 1.

FIG. 5 is a cross-sectional view of the boss part of the pump body of FIG. 1.

FIG. 6 is an enlarged cross-sectional view of the fastening part of the housing of the centrifugal pump of FIG. 1.

FIG. 7 is a bottom view of a pump body according to a second embodiment.

FIG. 8 is a cross-sectional view schematically illustrating a pump part of a centrifugal pump according to a third embodiment.

FIG. 9 is a cross-sectional view schematically illustrating a centrifugal pump according to a fourth embodiment.

FIG. 10 is a cross-sectional view schematically illustrating a centrifugal pump according to a fifth embodiment.

FIG. 11 is a cross-sectional view of a fastening part of a housing of the centrifugal pump of FIG. 10.

DETAILED DESCRIPTION

According to Japanese Unexamined Patent Application No. 2012-17712 described above, when a connection hole is drilled in the axial direction (with respect to the boss part of the partition wall) with a machining tool, such as a drill, the machining tool can perpendicularly abut the end surface of the boss part. However, when a connection hole is drilled in the oblique direction with respect to the boss part, the machining tool can diagonally abut the end surface of the boss part. This causes a radial load to be applied to the machining tool, which may undesirably deteriorate the workability. An object of the present disclosure is to improve workability when the connection hole is to be formed in the oblique direction with respect to the boss part of the partition wall.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

As an example of a first embodiment, a centrifugal pump 10 used as a purge pump mounted on a vehicle, such as an automobile, will now be described. The purge pump may increase the flow rate of a purge gas flowing from a canister to an intake passage of an internal combustion engine (an engine). FIG. 1 is a plan view schematically illustrating the centrifugal pump 10. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. The directions related to the centrifugal pump 10 are determined as shown by arrows in FIGS. 1 and 2. However, these directions do not limit the arrangement direction of the centrifugal pump 10.

As shown in FIG. 2, the centrifugal pump 10 includes a pump portion 12 and a motor portion 14 arranged in the axial direction (the vertical direction in FIG. 2). The centrifugal pump 10 may also be referred to as a “pump device” in the present disclosure.

A housing 16 of the centrifugal pump 10 includes a pump cover 18, a pump body 20, and a motor case 22. The pump cover 18 has a short cylindrical shape with a closed upper surface. The motor case 22 has a cylindrical shape. The motor case 22 includes a case cover 23 closing the lower surface opening of the motor case 22.

The pump body 20 has an annular plate shape. The pump body 20 is held between the pump cover 18 and the motor case 22. The upper surface of the outer peripheral part of the pump body 20 abuts the opening end surface of the pump cover 18 in a surface contact manner. Also, the lower surface of the outer peripheral part of the pump body 20 abuts the opening end surface of the motor case 22 in a surface contact manner.

An internal space formed by the pump cover 18 and the motor case 22 is partitioned into upper and lower spaces by the pump body 20. The pump cover 18, the motor case 22, and the case cover 23 may be made of, for example, a resin. The pump body 20 may be made of, for example, metal. A pump housing 26 is formed by the pump cover 18 and the pump body 20. A motor housing 28 is formed by the pump body 20, the motor case 22, and the case cover 23. The pump body 20 may also be referred to as a “partition wall” in the present disclosure.

The motor portion 14 may be a brushless motor. A rotor chamber 29, which has a substantially hollow cylindrical shape, is formed in the motor housing 28. The rotor chamber 29 houses, for example, a stator 30 and a rotor 32. The stator 30 has a cylindrical shape, and is concentrically and fixedly disposed in the motor case 22. The stator 30 includes, for example, a stator core and a stator coil. A bearing holder 34, which is substantially disk-shaped, is disposed horizontally at the lower end of the motor case 22. A bearing portion 34 a, which has a short cylindrical shape, is concentrically formed with the center of the bearing holder 34. The bearing holder 34 may be made of, for example, metal.

The rotor 32 is concentrically and rotatably disposed in the hollow part of the stator 30. The rotor 32 includes a rotor shaft 36 and permanent magnets 38. The rotor shaft 36 may be made of, for example, a metal, and may be composed of a solid shaft. The permanent magnets 38 are arranged so that multiple magnetic poles are lined up in the circumferential direction. The permanent magnets 38 may be arranged at a lower side of the rotor shaft 36, as measured from the center part and in the axial direction of the rotor shaft 36. The upper end of the rotor shaft 36 is rotatably supported within the hollow part of the pump body 20 by an upper-side bearing 40. The lower end of the rotor shaft 36 is rotatably supported within the bearing portion 34 a of the bearing holder 34 by a lower-side bearing 41. Both bearings 40, 41 may be, for example, ball bearings. Both bearings 40, 41 may be injected with a grease. The upper-side bearing 40 may correspond to a bearing for rotatably supporting the rotor shaft 36 of the rotor 32 to the pump body 20. The pump body 20 may function as a bearing holder.

A control circuit (not shown) may be disposed between the case cover 23 and the bearing holder 34 within the motor case 22. The motor case 22 may include an electric connector. A connector of an external power source may be connected to the electric connector. The rotor 32 may be rotated and driven by electric power supplied from an external power source to the control circuit.

FIG. 3 is a cross-sectional view schematically illustrating the pump portion 12 of the centrifugal pump 10. As shown in FIG. 3, a pump chamber 44, which has a substantially hollow disc shape, is formed within the pump housing 26. An intake port 46, which has a hollow cylindrical shape and projects upward, is formed in the central part of the pump cover 18. An intake opening 47, which communicates the inside of the pump chamber 44 with the outside, is formed inside the intake port 46.

A discharge port 53, which has a hollow cylindrical shape, is formed on the right side of the rear part of the pump cover 18. The discharge port 53 projects outwardly and tangentially from the outer peripheral part of the pump cover 18 in a plan view. That is, it projects outward in the clockwise direction (the right direction in FIG. 1). A discharge opening 54 is formed inside the discharge port 53. The discharge opening 54 is in fluid communication with a rear end of the pump chamber 44.

An impeller 56 is rotatably housed in the pump chamber 44. The impeller 56 includes a main plate 56 a and a plurality of blades 56 b. The main plate 56 a has a disc shape. The blades 56 b are formed on the upper surface of the main plate 56 a at predetermined intervals in the circumferential direction. A slight gap may be set between a lower surface of the main plate 56 a and the upper surface of the pump body 20. Each blade 56 b has a plate shape that extends in a standing state and radially on the upper surface of the main plate 56 a. The impeller 56 may be made of, for example, a resin

As shown in FIG. 2, the impeller 56 is concentrically and integrally connected to the leading end of the rotor shaft 36 of the rotor 32 (i.e. upper end of the rotor shaft 36 in FIG. 2). Consequently, the impeller 56 rotates with the rotor 32. The impeller 56 may be rotated clockwise in a plan view.

The motor portion 14 may be driven by electric power supplied from an external power source. Upon supply of the electric power, the impeller 56 rotates together with the rotor 32, so that a purge gas is taken into the pump chamber 44 via the intake opening 47. The purge gas is pressurized by the rotation of the impeller 56, and then discharged from the discharge opening 54. In this way, a purge gas may be pumped by the centrifugal pump 10.

As shown in FIGS. 3 and 4, the pump body 20 includes a partition wall 60 and a boss part 62. The partition wall 60 has an annular plate shape. The boss part 62 has a substantially cylindrical shape. The boss part 62 extends downward from the center part of the partition wall 60. The rotor shaft 36 is rotatably supported within the boss part 62 by the upper-side bearing 40. The boss part 62 includes a main part 63 and a projection part 64. The main part 63 has a cylindrical shape. The projection part 64 projects radially from the lateral section of the main part 63. The projection part 64 has a conical shape and is formed concentrically with the boss part 62. The projection part 64 includes an inclined surface section 65 that slopes radially inward moving axially downward toward the leading end direction (lower direction in FIG. 3) of the boss part 62. The inclined surface section 65 may be linear in cross sectional view as shown in FIG. 3.

A linear connection hole 67 extends through the boss part 62 from the rotor chamber 29 to the pump chamber 44 and provides fluid communication therebetween. A rotor chamber side opening end 67 a of the connection hole 67 opens along the inclined surface section 65 of the projection part 64. A pump chamber side opening end 67 b of the connection hole 67 is positioned proximal the upper-side bearing 40. For instance, the pump chamber side opening end 67 b may be positioned proximal the opening end, opening on the pump chamber 44 side of a hollow part 62 a of the boss part 62.

The connection hole 67 is formed along a straight line 67L orthogonal or substantially orthogonal to the inclined surface section 65 of the projection part 64. The straight line 67L defines a central axis or center line of the connection hole 67. As shown in FIG. 5, the connection hole 67 may be formed by drilling along line 67L. For instance, it may be formed by rotating a machining tool 68 in a state where the machining tool 68 abuts the inclined surface section 65 of the projection part 64 of the boss part 62 orthogonally or substantially orthogonally to the inclined surface section 65. A plurality of connection holes 67 may be formed in the inclined surface section 65.

As shown in FIG. 2, the pump cover 18 and the motor case 22 have the same outer diameter or substantially the same outer diameter. The pump body 20 has an outer diameter larger than both the outer diameter of the pump cover 18 and the outer diameter of the motor case 22. Therefore, the outer peripheral portion of the partition wall 60 of the pump body 20 may project radially outward relative to both the pump cover 18 and the motor case 22. As a result, a heat radiating part 61, which has an annular shape and is exposed from the housing 16 to the outside, is provided (see FIG. 1). The pump body 20 may be made of a material having a higher thermal conductivity than that of the motor case 22. A metal material having high thermal conductivity used for the pump body 20 may be, for example, aluminum.

As shown in FIG. 3, a first positioning portion 70 for concentrically positioning both the pump body 20 and the pump cover 18 is provided between the pump body 20 and the pump cover 18. The first positioning portion 70 includes a first annular projection 72 and an inner peripheral corner part 73. The first annular projection 72 is concentrically formed on an upper surface of the partition wall 60, near the outer periphery of the partition wall 60 of the pump body 20. The first annular projection 72 has an annular shape. The inner peripheral corner part 73 is an opening end of the pump cover 18. The first annular projection 72 is fitted, with almost no gap, within the inner peripheral corner part 73 of an opening end of the pump cover 18. Thus, the pump body 20 and the pump cover 18 are concentrically arranged.

A second positioning portion 75 for concentrically positioning both the pump body 20 and the motor case 22 is provided between the pump body 20 and the motor case 22. The second positioning portion 75 includes a second annular projection 76 and a fitting part 77. The second annular projection 76 is concentrically formed with the center, in the radial direction, of the lower surface of the partition wall 60 of the pump body 20. The second annular projection 76 has an annular shape. The fitting part 77 projects radially inward from the opening end of the motor case 22. The fitting part 77 has a flange shape. The second annular projection 76 is fitted within the fitting part 77 of the motor case 22, with almost no gap formed therebetween. Thus, the pump body 20 and the motor case 22 are concentrically arranged.

As shown in FIG. 3, a first sealing member 80 is provided between the pump body 20 and the pump cover 18. The first sealing member 80 may comprise an O-ring for elastically sealing the space between facing surfaces of the pump body 20 and the pump cover 18. The first sealing member 80 is fitted in an upper annular groove 81 formed on an opening end surface of the pump cover 18.

A second sealing member 83 is provided between the pump body 20 and the motor case 22. The second sealing member 83 may comprise an O-ring for elastically sealing the space between facing surfaces of the pump body 20 and the motor case 22. The second sealing member 83 is fitted in a lower annular groove 84 formed on an opening end surface of the motor case 22.

FIG. 6 is a cross-sectional view of a fastening part 85 of the housing 16. As shown in FIG. 6, the fastening part 85 is formed on an outer peripheral portion of the housing 16. Although the fastening part 85 is omitted in FIGS. 1, 2, etc., the fastening part 85 may be formed at a plurality of places (for example, three places) at predetermined intervals in the circumferential direction of the housing 16. The fastening part 85 includes an upper fastening piece 86 projecting radially outward from the opening end of the pump cover 18, a middle fastening piece 87 projecting radially outward from a peripheral end of the pump body 20, and a lower fastening piece 88 projecting radially outward from an opening end of the motor case 22. The upper fastening piece 86 and the lower fastening piece 88 are fastened by a tapping screw 90 with the middle fastening piece 87 sandwiched therebetween. Thus, the pump cover 18 and the motor case 22 are fastened together with the pump body 20 sandwiched therebetween. The tapping screw 90 may also be referred to as a “fastening member” in the present disclosure.

According to the first embodiment, when a connection hole 67 is drilled in the boss part 62 of the pump body 20 in the oblique direction, the machining tool 68, such as a drill bit, may abut the inclined surface section 65 of the projection part 64 of the boss part 62 orthogonally or substantially orthogonally. Therefore, when a connection hole 67 is to be drilled in a direction oblique to the boss part 62 of the pump body 20, workability may be improved as compared with that of Japanese Unexamined Patent Application No. 2012-17712.

When grease is injected into the upper-side bearing 40, gas in the pump chamber 44 (specifically, the gap between the pump body 20 and the impeller 56) flows through the connection hole 67, rather than through the upper-side bearing 40. Since the gas tends to bypass the upper-side bearing 40, grease loss from the bearing may be suppressed.

Since the projection part 64 projects radially from the lateral section of the boss part 62, the rigidity of the boss part 62 supporting the upper-side bearing 40 may be increased as compared with the case where a projection part 64 does not project from the boss part 62. As a result, axial vibrations of the rotor shaft 36 of the rotor 32 may be suppressed. Therefore, it is possible to suppress an increase in the amount of heat generated by the upper-side bearing 40 and to suppress deterioration of the upper-side bearing 40 due to such heat. As a result, the life of the pump may be improved.

The projection part 64, which is formed concentrically with the boss part 62, has a conical shape. Accordingly, a machining tool 68, such as a drill bit, may abut the inclined surface section 65, which is the lateral section of the projection part 64 having a conical shape, in an orthogonal or substantially orthogonal direction.

The pump chamber side opening end 67 b of the connection hole 67 is positioned in the vicinity of the hollow part 62 a of the boss part 62. Accordingly, the connection hole 67 can be connected with a low-pressure side of the pump chamber 44. Therefore, when grease is injected into the upper-side bearing 40, a rise of the pressure of the rotor chamber 29 may be suppressed, thereby further suppressing grease loss from the upper-side bearing 40. Here, the vicinity of the hollow part 62 a of the boss part 62 means that the pump chamber side opening end 67 b of the connection hole 67 is positioned further radially inward than the position of an the rotor chamber side opening end 67 a of the connection hole 67.

Further, the pump body 20 is made of a material having a higher thermal conductivity than the motor case 22. Additionally, the heat radiating part 61 is exposed to the outside. Accordingly, heat generated by the upper-side bearing 40 may be radiated to the outside via the pump body 20. Thus, thermal deterioration of the upper-side bearing 40 may be suppressed, thereby improving the life of the centrifugal pump 10.

The centrifugal pump 10 is provided with the first positioning portion 70 for concentrically positioning the pump body 20 and the pump cover 18. The centrifugal pump 10 is also be provided with the second positioning portion 75 for concentrically positioning the pump body 20 and the motor case 22. Accordingly, the pump body 20 and the pump cover 18 are concentrically arranged by the first positioning portion 70, and the pump body 20 and the motor case 22 are concentrically arranged by the second positioning portion 75. Thus, the pump body 20, the pump cover 18, and the motor case 22 are coaxial aligned. This may improve the flow rate accuracy of the centrifugal pump 10. Further, an increase in heat generation by the upper-side bearing 40 may be suppressed by suppressing axial vibrations of the rotor shaft 36 of the rotor 32. Furthermore, thermal deterioration of the upper-side bearing 40 may be suppressed. As a result, the life of the centrifugal pump 10 may be improved.

The centrifugal pump 10 is provided with the first sealing member 80 for face-sealing the pump body 20 and the pump cover 18 and is also provided with the second sealing member 83 for face-sealing the pump body 20 and the motor case 22. Accordingly, the pump body 20 and the pump cover 18 are face-sealed by the first sealing member 80, and the pump body 20 and the motor case 22 are face-sealed by the second sealing member 83. Consequently, intrusion of foreign substances into the pump chamber 44 and the rotor chamber 29 from the outside may be suppressed. An assembling load for face-sealing the first sealing member 80 and the second sealing member 83 is smaller than an assembling load for sealing the shaft. Therefore, the assemblability of the pump body 20 and the pump cover 18 and the assemblability of the pump body 20 and the motor case 22 may be improved.

The pump cover 18 and the motor case 22 are fastened to each other, with the pump body 20 sandwiched therebetween. Therefore, by fastening the three parts (i.e., the pump cover 18 and the motor case 22 are fastened together with the pump body 20 therebetween), the number of parts required for fastening and the number of assembly steps may be reduced, as compared with the case where each of two parts are fastened together.

A second embodiment that includes a modification of the boss part 62 of the pump body 20 of the first embodiment (see FIG. 4) will now be described. Accordingly, the modified parts will be described, while the substantially duplicate descriptions thereof will be omitted. FIG. 7 is a bottom view of a pump body 20. As shown in FIG. 7, in the second embodiment, a projection part 164 of a boss part 162 of the pump body 20 has a hexagonal pyramid shape and is formed concentrically with the boss part 162. Six inclined surface sections 165, each inclined radially inward moving downward toward the leading end of the boss part 162 (in the direction of the front side of the paper in FIG. 7), may be formed on the surface of the projection part 164. Each inclined surface section 165 may be planar. The connection hole 67 is formed with a straight line orthogonal or substantially orthogonal to one inclined surface section 165 of the six inclined surface sections 165 as a center line. A plurality of connection holes 67 may be formed on one inclined surface section 165. Further, a connection hole 67 may be formed in two or more inclined surface sections 165 of the six inclined surface sections 165.

A third embodiment that includes a modification of the second positioning portion 75 of the first embodiment (see FIG. 3) will now be described. Accordingly, the modified parts will be described, while the substantially duplicate descriptions thereof will be omitted. FIG. 8 is a cross-sectional view schematically showing a pump part of a centrifugal pump. As shown in the third embodiment of FIG. 8, a second positioning portion 175 for concentrically positioning the pump body 20 and the motor case 22 is provided. The second positioning portion 175 includes a middle stage part 176 and a fitting part 177. The middle stage part 176 is formed between the leading end of the main part 63 of the boss part 62 of the pump body 20 and the projection part 64. The fitting part 177 project radially inward from a position near the opening end of the motor case 22. The fitting part 177 has a flange-like shape. The middle stage part 176 is fitted within the fitting part 177 of the motor case 22, with almost no gap formed therebetween. Accordingly, the pump body 20 and the motor case 22 are concentrically arranged. A vent hole 178 penetrating in the vertical direction is formed in the fitting part 177. In particular, vent hole 178 is formed at a position corresponding to the connection hole 67 of the pump body 20.

A fourth embodiment that includes a modification of the supporting structure of the rotor 32 of the first embodiment (see FIG. 2) will now be described. Accordingly, the modified parts will be described, and the substantially duplicate descriptions thereof will be omitted. FIG. 9 is a cross-sectional view schematically showing a centrifugal pump. As shown in FIG. 9, in the fourth embodiment, the rotor shaft 36 of the rotor 32 is supported by the pump body 20 side only. That is, a lower-side bearing 41 on the bearing holder 34 for supporting the lower end of the rotor shaft 36 and the boss part 62 of the bearing holder 34 of the first embodiment (see FIG. 2) are omitted. Instead, the rotor shaft 36 is rotatably supported with respect to the boss part 62 of the pump body 20 by two vertically stacked bearings 40.

A fifth embodiment that includes a modification of the pump body 20 (see FIG. 2) and a fastening part 85 (see FIG. 6) of the first embodiment will now be described. Accordingly, the modified parts will be described, and the substantially duplicate descriptions thereof will be omitted. FIG. 10 is a cross-sectional view schematically showing a centrifugal pump. As shown in FIG. 10, in the fifth embodiment, the heat radiating part 61 of the pump body 20 of the first embodiment (see FIG. 2) is omitted. In particular, pump body 20 has an outer diameter smaller than the outer diameter of both the pump cover 18 and the motor case 22. The outer diameter of the pump body 20 is larger than the outer diameter of both the first sealing member 80 and the second sealing member 83. A peripheral end of the pump body 20 is covered by a peripheral wall 21 formed in an outer peripheral part of an opening end of the motor case 22. The upper end surface of the peripheral wall 21 abuts the opening end surface of the pump cover 18 in a surface contact manner.

FIG. 11 is a cross-sectional view showing a fastening part of a housing. As shown in FIG. 11, according to the fifth embodiment, a fastening part 185 is fastened by fastening the upper fastening piece 86 of the pump cover 18 and the lower fastening piece 88 of the motor case 22 with the tapping screw 90. In the fifth embodiment, the middle fastening piece 87 of the pump body 20 of the first embodiment (see FIG. 6) is omitted. Instead, a portion corresponding to the middle fastening piece 87 is formed integrally with the lower fastening piece 88. According to the fifth embodiment, the pump cover 18 and the motor case 22 are fastened together, with the pump body 20 sandwiched therebetween.

The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the present disclosure. For example, the pump device of the present disclosure may be applied to a pump device used for pumping a gas other than a purge gas such as air. The present disclosure may also be applied to a pump device other than a centrifugal pump. Further, the brushless motor of the motor portion 14 may be replaced with a bushed motor.

The axial cross section of the inclined surface section 65 on the projection part 64 of the boss part 62 of the pump body 20 is not limited to a planar surface, and may instead be a gentle convex arc shape, a gentle concave arc shape, etc. The projection part 164 of the boss part 162 of the pump body 20 may be changed to any appropriate polygonal pyramid shape, such as a triangular pyramid shape or a pentagonal pyramid shape. The inclined surface section 165 on the projection part 164 of the boss part 162 is not limited to a plane, but may instead be, for example, a gentle convex curved surface or a gentle concave curved surface. The projection part of the boss part may have a shape other than a conical shape or a polygonal pyramid shape. The projection part of the boss part may have at least one inclined surface in a part of the lateral section. The inclined surface may be a plane, a gentle convex curved surface, a gentle concave curved surface, etc. Further, the inclined surface may have the same cross section in one direction, for example, a gentle convex arc shape or a gentle concave circular arc shape.

The material having a high thermal conductivity of the pump body 20 may be, for example, a resin such as a carbon-containing resin. The heat radiating part 61 of the pump body 20 may not be continuously formed over the whole circumference of the pump body 20, but instead may be intermittently formed. At least a part of the outer peripheral surface of the pump body 20 may be exposed to the outside so as to act as a heat radiating part.

The same sealing member may be used for both the first sealing member 80 and the second sealing member 83. Alternatively, sealing members having different gauges, inner diameters, materials, etc. may be used.

The fastening member is not limited to the tapping screw 90. Instead, bolts and nuts, or the like, may be used. Further, the pump cover 18 and the motor case 22 may be fastened together or individually to the pump body 20.

In the present disclosure, various aspects and embodiments are disclosed. A first aspect is a pump device comprising a partition wall that provides a partition between a rotor chamber and a pump chamber. The pump device also comprises a motor case, a pump cover, and a bearing. The rotor is rotatably disposed in the rotor chamber. The impeller is coupled to the rotor and is rotatably disposed in the pump chamber. The motor case forms the rotor chamber together with the partition wall. The pump cover forms the pump chamber together with the partition wall. The bearing rotatably supports the rotor shaft of the rotor with respect to the partition wall. The partition wall has a boss part that projects from the partition wall body part to the rotor chamber side. The boss part supports the bearing. A projection part projects from a lateral section of the boss part. The projection part has an inclined surface section inclined radially inward toward the leading end side of the boss part. The boss part has formed therein a connection hole. The connection hole extends from the rotor chamber to the pump chamber. A rotor chamber side opening end of the connection hole opens to the inclined surface section.

According to the first aspect, when the connection hole is drilled in the boss part of the partition wall in the oblique direction, the machining tool, such as a drill bit, may abut the inclined surface section of the projection part of the boss part orthogonally or substantially orthogonally. Therefore, when the connection hole is drilled in the oblique direction in the boss part of the partition wall, workability may be improved, as compared with that of Japanese Unexamined Patent Application No. 2012-17712. Further, when grease is injected into the bearing, gas in the pump chamber flows through the connection hole, thereby bypassing the bearing. This may suppress grease loss from the bearing. Further, since the projection part projects from the lateral section of the boss part, the rigidity of the boss part supporting the bearing may be increased, compared with the case where the projection part does not project from the boss part. Thereby, axial vibrations of the rotor shaft of the rotor may be suppressed. Therefore, it is possible to suppress an increase in the amount of heat generated by the bearing, thereby suppressing deterioration of the bearing due to heat. As a result, the life of the pump device may be improved.

A second aspect is a pump device according to the first aspect, wherein the projection part has a conical shape or a polygonal pyramid shape concentrically arranged with the boss portion.

According to the second aspect, the machining tool, such as a drill bit, may abut the inclined surface section, which is a lateral section of the projection part having a conical shape or polygonal pyramid shape, in an orthogonal or substantially orthogonal direction. The “conical shape” used in the present disclosure may include a truncated cone shape. Further, the “polygonal pyramid shape” used in the present disclosure may include a polygonal pyramid trapezoidal shape.

A third aspect is a pump device according to the first or second aspect, wherein the pump chamber side opening end of the connection hole is positioned in the vicinity of a hollow part of the boss part.

According to the third aspect, the connection hole is connected to a low-pressure side of the pump chamber. Therefore, when grease is injected into the bearing, a rise in the pressure of the rotor chamber may be suppressed, thereby suppressing grease loss from the bearing.

A fourth aspect is a pump device according to any one of the first to third aspects, wherein the partition wall is made of a material having a higher thermal conductivity than that of the motor case, and a part of the partition wall is exposed to the outside.

According to the fourth aspect, heat generated by the bearing may be radiated to the outside via the partition wall. Thus, thermal deterioration of the bearing may be suppressed, and the life of the pump device may be improved.

A fifth aspect is a pump device according to any one of the first to fourth aspects, wherein the pump device is provided with a first positioning portion for concentrically arranging the partition wall and the pump cover. The pump device may also be provided with a second positioning portion for concentrically arranging the partition wall and the motor case.

According to the fifth aspect, the partition wall and the pump cover are positioned concentrically by the first positioning portion, and the partition wall and the motor case are positioned concentrically by the second positioning portion. Consequently, the coaxial alignment of three components, the partition wall, the pump cover, and the motor case, may be improved. Accordingly, the flow rate accuracy of the centrifugal pump may be improved. Further, an increase in the generation of heat by the bearing may be suppressed by suppressing the axial vibrations of the rotor shaft of the rotor. Furthermore, thermal deterioration of the bearing may be suppressed. As a result, the life of the pump device may be improved.

A sixth aspect is a pump device according to any one of the first to fifth aspects, wherein the pump device is provided with a first sealing member for face-sealing the partition wall and the pump cover. The pump device is also be provided with a second sealing member for face-sealing the partition wall and the motor case.

According to the sixth aspect, the partition wall and the pump cover are face-sealed by the first sealing member, and the partition wall and the motor case are face-sealed by the second sealing member. Thus, intrusion of foreign substances into the pump chamber and the rotor chamber from the outside may be suppressed. An assembling load for face-sealing the first sealing member and the second sealing member may be smaller than an assembling load for sealing the shaft. Accordingly, the assemblability of the partition wall and the pump cover and the assemblability of the partition wall and the motor case may be improved.

A seventh aspect is a pump device according to any one of the first to sixth aspects, wherein the pump cover and the motor case are fastened together with the partition wall sandwiched therebetween.

According to the seventh aspect, by fastening the pump cover and the motor case together with the partition wall sandwiched therebetween, the number of parts required for fastening and the number of assembly steps may be reduced compared with the case where each of a pair of parts need to be fastened together.

While the embodiments of the disclosure have been described with reference to specific configurations, it will be apparent to those skilled in the art that many alternatives, modifications, and variations may be made without departing from the scope of the present disclosure. Accordingly, embodiments of the present disclosure are intended to embrace all such alternatives, modifications, and variations that may fall within the spirit and scope of the appended claims. Embodiments of the present disclosure should not be limited to the representative configurations, but may be modified as appropriate. 

1. A pump device, comprising: a rotor chamber and a rotor rotatably disposed in the rotor chamber; a pump chamber and an impeller rotatably disposed in the rotor chamber, wherein the impeller is coupled to the rotor and is configured to rotate with the rotor; a partition wall defining a partition between the rotor chamber and the pump chamber; a motor case that forms the rotor chamber together with the partition wall; a pump cover that forms the pump chamber together with the partition wall; and a bearing that rotatably supports a rotor shaft of the rotor with respect to the partition wall; wherein: a boss part projects from the partition wall toward the rotor chamber and supports the bearing; a projection part extends from a lateral section of the boss part, the projection part having an inclined surface section inclined radially inward toward a leading end side of the boss part; the boss part has formed therein a connection hole that extends from the rotor chamber to the pump chamber; and a rotor chamber side opening end of the connection hole opens along the inclined surface section.
 2. The pump device according to claim 1, wherein the projection part has a conical shape or a polygonal pyramid shape formed concentrically with the boss portion.
 3. The pump device according to claim 1, wherein a pump chamber side opening end of the connection hole is positioned radially nearer a hollow part of the boss part than the rotor chamber side opening end of the connection hole.
 4. The pump device according to claim 1, wherein: the partition wall is made of a material having a thermal conductivity greater than a thermal conductivity of a material of the motor case, and a portion of the partition wall is exposed to the outside of the motor case.
 5. The pump device according to claim 1, wherein the pump device further comprises: a first positioning portion for concentrically arranging the partition wall and the pump cover; and a second positioning portion for concentrically arranging the partition wall and the motor case.
 6. The pump device according to claim 1, wherein: the pump device includes a first sealing member for face-sealing the partition wall and the pump cover, and the pump device includes a second sealing member for face-sealing the partition wall and the motor case.
 7. The pump device according to claim 1, wherein the pump cover and the motor case are fastened together with the partition wall sandwiched therebetween.
 8. The pump device according to claim 1, wherein the connection hole extends in a direction oriented perpendicular to the inclined surface section.
 9. The pump device according to claim 1, wherein the connection hole extends in a direction non-parallel to a central axis of the rotor shaft. 